Anti-roll thrust system for vehicles

ABSTRACT

A thruster system is provided for a vehicle that can be used to reduce the roll propensity of a motor vehicle. The system utilizes a control system and multiple sets of thrusters which are strategically placed upon the vehicle. The control system is provided for detecting a potential roll condition and activates selected ones of the thrusters to produce a necessary thrust force for counteracting roll forces.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/562,143, filed on Apr. 14, 2004, the disclosure of which isincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an anti-roll system for a vehicle, andmore particularly, to an anti-roll system which employees thrustersmounted to the vehicle for resisting roll forces acting on a vehicle.

BACKGROUND OF THE INVENTION

Auto manufacturers have developed systems to aid in vehicle stability,such as variable ride height suspension systems, anti-lock brakingsystems and electronic stability control systems. Variable ride heightsuspension systems are capable of lowering a vehicle's height whiledriving at high speeds and while making sharp corners in order to reducethe height of the vehicles center of gravity and thereby reduce itslikelihood of a rollover. Anti-lock braking systems control the brakingforces applied to prevent the wheels from locking up and/or skidding andthereby helping the driver maintain control of the vehicle. Electronicstability control systems are capable of altering the stiffness of thevehicle suspension system in response to certain vehicle drivingconditions.

In addition, auto manufacturers have developed further vehicle safetyfeatures to help protect the passengers in the event of an accident.These systems include seat belts and side and front airbags. Althoughall of the above systems have proven to be effective at improvingvehicle stability and in protecting occupants, there is still a need toimprove the vehicle roll resistance.

SUMMARY OF THE INVENTION

The present invention is directed to a thruster system that is designedto reduce the roll propensity of a motor vehicle when needed. The systemincludes a first thruster mounted on a first side of the motor vehicleand a second thruster mounted on a second side of the motor vehicle. Acontroller system is provided for detecting a potential roll conditionof the vehicle and activating one of the first and second thrusters forgenerating a counteracting force for resisting the detected potentialroll condition.

According to one aspect of the present invention, the first and secondthrusters are each mounted in a side pillar of the motor vehicle.

According to yet another aspect of the present invention, the first andsecond thrusters are rocket motors.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a schematic view of a vehicle having a thruster located in theroof of a vehicle for applying a roll resisting force to the vehicle;

FIG. 2 is a schematic diagram of a vehicle having a thruster systemprovided as an add-on device to a motor vehicle according to theprinciples of the present invention;

FIG. 3 is a side view illustrating exemplary potential mountinglocations of the thrusters according to the principles of the presentinvention;

FIG. 4 is a schematic illustration of a vehicle force diagram;

FIG. 5 is a force diagram illustrating the relevant forces relating to avehicle with the anti-roll thrusters during a roll condition;

FIG. 6 is an illustration of the instantaneous critical roll rateutilized for determining activation of the thrusters according to theprinciples of the present invention;

FIG. 7 is a flow diagram illustrating an activation algorithm that isestablished based on the instantaneous critical roll rate value asdetermined in FIG. 6; and

FIG. 8 is a graph illustrating the target design space of requiredthrust force and impulse to satisfy the design criteria according to theprinciples of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

With reference to FIG. 1, a vehicle 10 is shown experiencing roll forcesrelative to a surface 12 with the vehicle 10 having a thruster 14activated for applying a force (F_(T)) for resisting the roll forces ofthe vehicle 10. According to the present invention, the vehicle 10 isprovided with one or more thrusters 14 provided on each side of thevehicle and mounted within one of the A pillar, B pillar, or C pillar ofthe vehicle. It should be understood that the thrusters can also bemounted to other advantageous locations of the vehicle including theengine compartment, trunk, door, or anywhere else where the thrusterforce is desired and where packaging space can be found for thethrusters. As illustrated in FIG. 3, multiple thrusters 14L, 14R can beprovided on each side of the vehicle. It should be understood thatalthough thrusters 14L are illustrated in FIG. 3 on the left hand sideof the vehicle, thrusters 14R are mounted to the right hand side of thevehicle in the same manner as illustrated in FIG. 3. The thrusters 14L,14R are controlled by a central processor unit 16 which receives inputsignals representative of vehicle driving condition. From these vehicledriving conditions, the central processor unit 16 is capable ofdetermining the roll forces acting on the vehicle and activating thethrusters 14L, 14R in order to apply an anti-roll thruster force F_(T)for resisting the roll forces.

As illustrated in FIG. 3, thruster doors 18 can be employed in order tocover the thrusters 14L, 14R and provide the vehicle with a refinedaesthetic appearance. The thruster doors 18 can be designed to hingedlyopen or otherwise open or release upon activation of the thrusters 14L,14R. The direction of the thrust force can be adjusted for the vehiclemounting location of the thrusters and other factors. As illustrated inFIG. 2, the thrusters 14L′, 14R′ can also be employed as an add-ondevice which can be mounted to the vehicle roof and can possibly even beemployed with a vehicle roof rack system. The direction of the nozzlesof the thrusters 14L′, 14R′ can be designed such that they would not beinterfered with by cargo supported on the roof rack.

The present invention utilizes an equivalent design strategy in order toprovide a thruster system which can apply a force to the vehicle inorder to provide the vehicle in question with equivalent roll forcecharacteristics to predetermined vehicle roll force characteristics. Inother words, the thrusters 14 apply a force F_(T) so as to give thevehicle an equivalent roll force characteristic as an exemplary rollperformance target.

In utilizing the equivalent design strategy, three different designstrategies are discussed in greater detail herein. First is theequivalent static stability factor (SSF) design strategy, the second isthe equivalent critical sliding velocity (CSV) design strategy, and thethird is the equivalent critical roll rate (CRR) design strategy. Toillustrate the effect of these design strategies on the thruster design,as well as other special features of the invention, an exemplary vehicleand exemplary roll performance target are used in the examples discussedbelow.

For the equivalent SSF (static stability factor) design strategy, thethrusters 14L, 14R are designed such that they will produce enoughthrust to make up the difference of the static stability factor (SSF)values between the exemplary vehicle and the target SSF value. The sumof the SSF value and the make-up part contributed by the thrusters iscalled the effective static stability factor (ESSF). The staticstability factor equation is:

$\frac{T}{2h_{CG}}$

The SSF combines track width and center of gravity, two key componentsof vehicle stability. The SSF is a measure that equals one-half the.track width (T) divided by the height of the center of gravity (h_(CG))above the road. With reference to FIG. 4, the necessary roll conditionfor a vehicle utilizing the SSF is:

${{F_{TRIP}h_{CG}} - {{mg}\left( \frac{T}{2} \right)}} > 0$which results in

$\frac{F_{TRIP}}{mg} > \frac{T}{2h_{CG}}$where T is the track width, m is the vehicle mass, g is gravity, h_(CG)is the height of the center of gravity of the vehicle, and F_(TRIP) isthe trip force applied to the vehicle that would lead to roll condition.

Since in the above equation, when the value of the SSF factor (the righthand term in the above equation) is large, the magnitude of the tripforce (F_(TRIP)) must also be large in order to cause a vehicle rollcondition. Thus, the larger the SSF factor, the less likely the vehicleis to have a roll event.

Table 1 below provides exemplary data from a target vehicle and anexample vehicle relevant to the static stability factor. In particular,the target SSF value calculates to be 1.37 while the SSF value for theexample vehicle is 1.07.

TABLE 1 T h_(CG) Mass I_(CG) mm mm kg kg-m{circumflex over ( )}2 SSFTarget Values 1467 535 1577 568 1.37 Example Vehicle 1419 664 1729 5801.07

Employing the equivalent SSF design strategy, the necessary rollcondition for the exemplary vehicle becomes:

$\left\lbrack \frac{F_{TRIP}}{mg} \right\rbrack_{EXAMPLE} > {\overset{\overset{ESSF}{︷}}{\left\lbrack \frac{T}{2h_{CG}} \right\rbrack_{EXAMPLE} + \left\lbrack \frac{F_{T}X}{{mgh}_{CG}} \right\rbrack}}_{EXAMPLE}$where X is the average distance from the thrusters to the tripping pointperpendicular to the vehicle roll axis, while the necessary rollcondition for the target vehicle is:

$\left\lbrack \frac{F_{TRIP}}{mg} \right\rbrack_{TARGET} > {\overset{\overset{SSF}{︷}}{\left\lbrack \frac{T}{2h_{CG}} \right\rbrack}}_{TARGET}$

In order to make these two conditions equivalent, their right hand termsmust be equal:

${\left\lbrack \frac{T}{2h_{CG}} \right\rbrack_{EXAMPLE} + \left\lbrack \frac{F_{T}X}{{mgh}_{CG}} \right\rbrack_{EXAMPLE}} = \left\lbrack \frac{T}{2h_{CG}} \right\rbrack_{TARGET}$which solved for the value of the force of the anti-roll thruster (F_(T)) results in the equation:

$F_{T} = {\left\lbrack {\left( \frac{{SSF}_{TARGET}}{{SSF}_{EXAMPLE}} \right) - 1} \right\rbrack\left( \frac{mgT}{2X} \right)_{EXAMPLE}}$

Thus, in order to make the example vehicle have an equivalent SSF valueto the target vehicle, the equation can be solved to obtain thecorresponding thruster specification as illustrated in Table 2reproduced below. From the above equation, the thrust force (F_(T)) ofthe thruster is calculated to be 1.75 kN. From this value, other designspecifications for the thruster, such as required mass flow rate andnozzle throat area can also be calculated based on the required thrustforce.

TABLE 2 SSF ESSF Target 1.37 1.37 Example Vehicle 1.07 1.07 ExampleVehicle W/Thruster - 1.07 1.37 Equivalent SSF Anti-Rollover ThrusterSpecification Equivalent SSF Thrust force, kN 1.75 Mass flow rate, kg/s3.51 Sonic speed of nitrogen gas at 600° K, m/s 499 Total nozzle throatarea, m{circumflex over ( )}2 0.0019 Throat diameter of one nozzledesign, mm 49 Throat diameter of two nozzles design, mm 35 Thrustingduration, msec ? Total gas mass, kg ? Activation threshold ?

For the equivalent critical sliding velocity (CSV) design strategy, thethrusters are so designed that they will produce just enough thrustforce to make up the difference of the CSV values between the examplevehicle and the target vehicle characteristics. The sum of the CSV valueand the make-up part contributed by the thrusters is called theeffective critical sliding velocity (ECSV). The critical slidingvelocity equation for a quarter turn roll is:

${CSV} = \sqrt{\frac{2{gI}_{O}}{{mh}_{CG}^{2}}\left( {\sqrt{\frac{T^{2}}{4} + h_{CG}^{2}} - h_{CG}} \right)}$where I_(O) is the vehicle's moment of inertia about the point ofapplication of the F_(TRIP) force. Specifically, the equation for themoment of inertia about this point is:

$I_{O} = {I_{CG} + {{m\left( {\frac{T^{2}}{4} + h_{CG}^{2}} \right)}.}}$

The relevant values for determining the CSV for the target vehicle andexample vehicle are provided in Table 3 where the value T is the trackwidth, the value h_(CG) is the height of the center of gravity of thevehicle, m is the mass of the vehicle, and I_(CG) is the moment ofinertia about the center of gravity of the vehicle.

TABLE 3 T h_(CG) Mass I_(CG) CSV mm mm kg kg-m{circumflex over ( )}2 SSFm/s Target 1467 535 1577 568 1.37 5.50 Example Vehicle 1419 664 1729 5801.07 4.18

The values provide a CSV value for the target vehicle of 5.5 and a CSVvalue for the example vehicle of 4.18. Utilizing the equivalent CSVdesign strategy, the equivalent CSV value for the example vehicle isdetermined by the equation:

$\lbrack{ECSV}\rbrack_{EXAMPLE} = \left\lbrack \sqrt{{CSV}^{2} + \frac{2I_{O}F_{T}X\;\hat{\theta}}{m^{2}h_{CG}^{2}}} \right\rbrack_{EXAMPLE}$where the value {circumflex over (θ)} is defined by the equation:

${\hat{\theta} = {{\frac{\pi}{2} - {\theta_{0}\mspace{14mu}{and}\mspace{14mu}\theta_{0}}} = {\tan^{- 1}\left( \frac{2h_{CG}}{T} \right)}}},$while the CSV value for the target is determined by the equation:

$\lbrack{CSV}\rbrack_{TARGET} = \left\lbrack \sqrt{\frac{2{gI}_{O}}{{mh}_{CG}^{2}}\left( {\sqrt{\frac{T^{2}}{4} + h_{CG}^{2}} - h_{CG}} \right)} \right\rbrack_{TARGET}$

By making the value of [ECSV]_(EXAMPLE) equal to the value[CSV]_(TARGET), the equation can be solved for the required force of theanti-roll thruster (F_(T)) according to the following equation:

$F_{T} = {\left\lbrack \frac{m^{2}h_{CG}^{2}}{2I_{O}X\hat{\theta}} \right\rbrack_{EXAMPLE}\left\{ {\lbrack{CSV}\rbrack_{TARGET}^{2} - \lbrack{CSV}\rbrack_{EXAMPLE}^{2}} \right\}}$

Table 4 below provides the results of the calculation utilizing theequivalent CSV design strategy as well as a comparison of the equivalentSSF design strategy. For the equivalent CSV design strategy, a thrustforce of 2.38 kN is determined to be necessary in order to provide theexample vehicle with an equivalent CSV value to the target vehicle. Fromthis value, the required mass flow rate and nozzle throat area are thencalculated based on required thrust force as illustrated in Table 4.

TABLE 4 CSV ECSV SSF ESSF m/s m/s Target 1.37 1.37 5.50 5.50 ExampleVehicle 1.07 1.07 4.18 4.18 Example Vehicle w/Thruster - 1.07 1.37 4.185.18 Equivalent SSF Example Vehicle w/Thruster - 1.07 1.48 4.18 5.50Equivalent CSV Equivalent Equivalent Thruster Specification SSF CSVThrust force, kN 1.75 2.38 Mass flow rate, kg/s 3.51 4.77 Sonic speed ofnitrogen gas at 600° K, m/s 499 499 Total nozzle throat area,m{circumflex over ( )}2 0.0019 0.0026 Throat diameter of one nozzledesign, mm 49 57 Throat diameter of two nozzles design, mm 35 41Thrusting duration, msec ? ? Total gas mass, kg ? ? Activation threshold? ?

For the equivalent critical roll rate (ECRR) design strategy, thethrusters are so designed that they will produce just enough thrustforce to make up the difference of the CRR (critical roll rate) valuebetween a given example vehicle and a target vehicle. The sum of the CRRvalue and the make-up part contributed by the force of the thrusters iscalled the effective critical roll rate (ECRR). The value of Θ₀ asillustrated in FIG. 4, which is the initial angle between the ground anda line extending between the center of gravity of the vehicle CG and theedge of the track width T for the example vehicle. For the critical rollrate calculation, the value:{dot over (θ)}₀≧CRR

Thus, the conservation of system energy provides the equation:

${\frac{1}{2}I_{O}{\overset{.}{\theta}}_{0}^{2}} \geq {{mg}\left( {r - {r\mspace{11mu}\sin\mspace{11mu}\theta_{0}}} \right)}$${{{or}\mspace{14mu}{\overset{.}{\theta}}_{0}} \geq \sqrt{\frac{2{mgr}}{I_{O}}\left( {1 - {\sin\mspace{11mu}\theta_{0}}} \right)}} = {CRR}$${{where}\mspace{14mu} r} = \sqrt{h_{CG}^{2} + \frac{T^{2}}{4}}$

-   -   where the value I₀ is the moment of inertia about the 0 point,        as illustrated in FIG. 5.

Table 5 provides the CRR values for the target vehicle and examplevehicle as well as providing the SSF and CSF values for these vehicles.

TABLE 5 T h_(CG) Mass I_(CG) CSV CRR mm mm kg kg-m{circumflex over ( )}2SSF m/s rad/s Target 1467 535 1577 568 1.37 5.50 2.48 Example Vehicle1419 664 1729 580 1.07 4.18 2.17

In order to increase the example vehicle's effective CRR value from 2.17rad/s to 2.48 rad/s, the target CRR, a thrust force of 1.01 kN isrequired using the equations:

$\begin{matrix}{\lbrack{ECRR}\rbrack_{EXAMPLE} = \left\lbrack \sqrt{{CRR}^{2} + \frac{2F_{T}X\hat{\theta}}{I_{O}}} \right\rbrack_{EXAMPLE}} \\{\lbrack{CRR}\rbrack_{TARGET} = \left\lbrack \sqrt{\frac{2{{mg}r}}{I_{O}}\left( {1 - {\sin\mspace{11mu}\theta_{0}}} \right)} \right\rbrack_{TARGET}}\end{matrix}$

-   -   wherein the value of the thrust force F_(T) can be determined        from the equation:

$F_{T} = {\left\lbrack \frac{I_{O}}{2X\hat{\theta}} \right\rbrack_{EXAMPLE}\left\{ {\lbrack{CRR}\rbrack_{TARGET}^{2} - \lbrack{CRR}\rbrack_{EXAMPLE}^{2}} \right\}}$

Table 6 provides a comparison between the equivalent SSF, equivalentCSV, and equivalent CRR design strategy and illustrates the requiredmass flow rate and nozzle throat area which are calculated based onrequired thrust force for each of these design strategies.

TABLE 6 CSV ECSV CRR ECRR SSF ESSF m/s m/s rad/s rad/s Target 1.37 1.375.50 5.50 2.48 2.48 Example Vehicle 1.07 1.07 4.18 4.18 2.17 2.17Example w/ART - 1.07 1.37 4.18 5.18 2.17 2.69 Equivalent SSF Examplew/ART - 1.07 1.48 4.18 5.50 2.17 2.85 Equivalent CSV Example w/ART -1.07 1.24 4.18 4.79 2.17 2.48 Equivalent CRR Equivalent EquivalentEquivalent Thruster Specification SSF CSV CRR Thrust force, kN 1.75 2.381.01 Mass flow rate, kg/s 3.51 4.77 2.03 Sonic speed of nitrogen gas at499 499 499 600° K, m/s Total nozzle throat area, m{circumflex over( )}2 0.0019 0.0026 0.0011 Throat diameter of one 49 57 38 nozzledesign, mm Throat diameter of two 35 41 27 nozzles design, mm Thrustingduration, msec ? ? ? Total gas mass, kg ? ? ? Activation threshold ? ? ?

Any one of the equivalent design strategies can be utilized or selectedfor determining the required thrusting duration of the thrusters 14L,14R. The following provides an example of the use of the effectivecritical roll rate (CRR) value to determine a required thrustingduration of the anti-roll thrusters 14L, 14R. The ECRR is essentiallythe minimum roll rate for the example vehicle to make a quarter rollagainst the thrust force of the thrusters 14L, 14R. The requiredthrusting duration and total gas mass can be calculated for each designstrategy as illustrated in Table 7.

TABLE 7 CSV ECSV CRR ECRR SSF ESSF m/s m/s rad/s rad/s Target 1.37 1.375.50 5.50 2.48 2.48 Example Vehicle 1.07 1.07 4.18 4.18 2.17 2.17Example Vehicle 1.07 1.37 4.18 5.18 2.17 2.69 w/Thruster - EquivalentSSF Example Vehicle 1.07 1.48 4.18 5.50 2.17 2.85 w/Thruster -Equivalent CSV Example Vehicle 1.07 1.24 4.18 4.79 2.17 2.48w/Thruster - Equivalent CRR Equivalent Equivalent Equivalent ThrusterSpecification SSF CSV CRR Thrust force, kN 1.75 2.38 1.01 Mass flowrate, kg/s 3.51 4.77 2.03 Sonic speed of nitrogen gas at 499 499 499600° K, m/s Total nozzle throat area, m{circumflex over ( )}2 0.00190.0026 0.0011 Throat diameter of one 49 57 38 nozzle design, mm Throatdiameter of two 35 41 27 nozzles design, mm Thrusting duration, msec 829743 986 Total gas mass, kg 2.9 3.5 2.0 Activation threshold ? ? ?

Using the effective critical roll rate to determine a required thrustingduration of the thrusters, the equation of motion is:I _(O) {umlaut over (θ)}+rmg cos θ+F _(T) X=0

-   -   where

$r = \sqrt{\frac{T^{2}}{4} + h_{CG}^{2}}$

-   -    with initial condition at time t₀ and terminal conditions at        time t_(e) being:        θ(t ₀)=θ₀ and {dot over (θ)}(t ₀)=ECRR

${\theta\left( t_{e} \right)} = {{\frac{\pi}{2}\mspace{14mu}{and}\mspace{14mu}{\overset{.}{\theta}\left( t_{e} \right)}} = 0}$

Each of the required values is illustrated in FIG. 5 which illustratesthe vehicle 10 in a critical position for a quarter roll. Beforereaching such a position, the gravity force acting at the mass center ofthe vehicle is against the roll. Once exceeding such a position, thegravity force will now help the roll and a vehicle will never recoverfrom a roll without the intervention of external forces. The activationcriterion for the thrusters 14L, 14R are determined by using theinstantaneous critical roll rate (ICRR) which is determined by theequation:

${\frac{1}{2}I_{O}{\overset{.}{\theta}}^{2}} \geq {m\;{g\left( {r - {r\mspace{11mu}\sin\mspace{11mu}\theta}} \right)}}$${{{or}\mspace{14mu}\overset{.}{\theta}} \geq \sqrt{\frac{2{mgr}}{I_{O}}\left( {1 - {\sin\mspace{11mu}\theta}} \right)}} = {ICRR}$${{where}\mspace{14mu} r} = \sqrt{h_{CG}^{2} + \frac{T^{2}}{4}}$

The example vehicle's instantaneous critical roll rate as a function ofthe roll angle is shown plotted in FIG. 6. In theory, the examplevehicle will never recover from a roll if its instantaneous roll rateexceeds the instantaneous critical roll rate as shown in FIG. 6.Accordingly, the activation threshold of the anti-roll thruster must beset lower than the instantaneous critical roll rate. One way todetermine the activation threshold is to set the threshold value equalto “s” times of the ICRR values, where “s” is a scaling factor which isless than, or equal to, one and greater than zero. Also plotted in FIG.6 is an example activation threshold which is 90 percent of theinstantaneous critical roll rate.

With reference to FIG. 7, an example activation algorithm is provided,in which at step S1 the roll rate of the vehicle is used to compare withan activation threshold that is established based on the ICRR value, asshown in FIG. 6. At step S2, if the roll rate of the vehicle has beengreater than a threshold value for more than t milliseconds (forexample, 5 milliseconds), and if the roll rate ({dot over (θ)}) isgreater than 0 (step S3), a corresponding set of thrusters (14L, stepS4) , on the left side of the vehicle, will be activated to generatethrust forces to resist the roll. If the roll rate {dot over (θ)} is notgreater than 0, then a second set of thrusters 14R, on the right side ofthe vehicle, are activated at step S5. For example, an activationthreshold of 1.95 RAD/s (i.e., 90 percent of the vehicle's CRR value) ischosen for all three designs, as illustrated in Table 8 below.

TABLE 8 CSV ECSV CRR ECRR SSF ESSF m/s m/s rad/s rad/s Target 1.37 1.375.50 5.50 2.48 2.48 Example vehicle 1.07 1.07 4.18 4.18 2.17 2.17Example vehicle 1.07 1.37 4.18 5.18 2.17 2.69 w/Thruster - EquivalentSSF Example vehicle 1.07 1.48 4.18 5.50 2.17 2.85 w/Thruster -Equivalent CSV Example vehicle 1.07 1.24 4.18 4.79 2.17 2.48w/Thruster - Equivalent CRR Equivalent Equivalent Equivalent ThrusterSpecification SSF CSV CRR Thrust force, kN 1.75 2.38 1.01 Mass flowrate, kg/s 3.51 4.77 2.03 Sonic speed of nitrogen gas at 499 499 499600° K, m/s Total nozzle throat area, m{circumflex over ( )}2 0.00190.0026 0.0011 Throat diameter of one 49 57 38 nozzle design, mm Throatdiameter of two 35 41 27 nozzles design, mm Thrusting duration, msec 829743 986 Total gas mass, kg 2.9 3.5 2.0 Activation threshold 1.95 1.951.95 (roll rate >90% CRR), rad

The method described above can be easily expanded to all types ofvehicles, including cars, trucks, vans, and sport utility vehicles. Foran example vehicle, the generalized equivalent SSF, CSV, and CRRformulas are as follows:

$\begin{matrix}{{ESSF}_{EXAMPLE} = \left\lbrack {\frac{T}{2h_{CG}} + \frac{F_{T}X}{{mgh}_{CG}}} \right\rbrack_{EXAMPLE}} \\{{ECSV}_{EXAMPLE} = \left\lbrack \sqrt{{\frac{2{gI}_{O}}{{mh}_{CG}^{2}}\left( {r - h_{CG}} \right)} + \frac{2I_{O}F_{T}X\hat{\theta}}{m^{2}h_{CG}^{2}}} \right\rbrack_{EXAMPLE}} \\{{ECCR}_{EXAMPLE} = \left\lbrack \sqrt{\frac{2{{mg}\left( {r - h_{CG}} \right)}}{I_{O}} + \frac{2F_{T}X\hat{\theta}}{I_{O}}} \right\rbrack_{EXAMPLE}}\end{matrix}$

Each of these generalized equivalent formulas are utilized to make agiven vehicle perform like a target vehicle or, according to apredetermined SSF, CSV, or CRR value. The required thrust force formulasthat makes a given vehicle perform like a target vehicle with respect toeach of the three design strategies is calculated according to thefollowing alternative equations.

$\left\lbrack F_{T} \right\rbrack_{EXAMPLE} = {{\left\lbrack {\left( \frac{{SSF}_{TARGET}}{{SSF}_{EXAMPLE}} \right) - 1} \right\rbrack{\left( \frac{mgT}{2X} \right)_{EXAMPLE}\left\lbrack F_{T} \right\rbrack}_{EXAMPLE}} = {{\left\lbrack \frac{m^{2}h_{CG}^{2}}{2I_{O}X\;\hat{\theta}} \right\rbrack_{EXAMPLE}{\left( {{CSV}_{TARGET}^{2} - {CSV}_{EXAMPLE}^{2}} \right)\left\lbrack F_{T} \right\rbrack}_{EXAMPLE}} = {\left\lbrack \frac{I_{O}}{2X\;\hat{\theta}} \right\rbrack_{EXAMPLE}\left( {{CRR}_{TARGET}^{2} - {CRR}_{EXAMPLE}^{2}} \right)}}}$

-   -   wherein, in the above equations,

${SSF} = \frac{T}{2h_{CG}}$${CSV} = \sqrt{\frac{2{gI}_{O}}{{mh}_{CG}^{2}}\left( {r - h_{CG}} \right)}$${CRR} = \sqrt{\frac{2\; m\; g}{I_{O}}\left( {r - h_{CG}} \right)}$I_(O) = I_(CG) + mr² $r = \sqrt{h_{CG}^{2} + \frac{T^{2}}{4}}$$\theta_{0} = {\tan^{- 1}\left( \frac{2h_{CG}}{T} \right)}$$\hat{\theta} = {\frac{\pi}{2} - \theta_{0}}$

The equivalent CRR design strategy can be further generalized using theprinciple of energy conservation. Specifically, the thrusters are sodesigned that they will do anti-roll work equivalent to the differencebetween the one-quarter turn roll-over kinetic energy of an examplevehicle and a target value. The anti-roll work done by the thrusters,W_(T), can be calculated as follows:

$W_{T} = {{\left( \frac{{CRR}_{TARGET}}{{CRR}_{EXAMPLE}} \right)^{2}\mspace{11mu}\left\lbrack {KE}_{C\;} \right\rbrack}_{EXAMPLE} - \left\lbrack {PE}_{C} \right\rbrack_{EXAMPLE}}$

-   -   where [KE_(C)]_(EXAMPLE) is the kinetic energy of the example        vehicle at its critical roll rate and [PE_(C)]_(EXAMPLE) is the        potential energy of the same example vehicle at its critical        roll angle:

$\left\lbrack {KE}_{C} \right\rbrack_{EXAMPLE} = {\frac{1}{2}\left\lbrack {I_{O}{CRR}^{2}} \right\rbrack}_{\overset{EXAMPLE}{\;}}$[PE _(C)]_(EXAMPLE) =[mg(r−h _(CG))]_(EXAMPLE)

-   -   and the required thrust force for the example vehicle can now be        inversely calculated using the following equation:

$W_{T} = {\left\lbrack {\int_{\theta_{0}}^{\frac{\pi}{2}}{F_{T}X{\mathbb{d}\theta}}} \right\rbrack_{EXAMPLE} = \left\lbrack {\int_{t_{0}}^{t_{e}}{F_{T}X\;\overset{.}{\theta}{\mathbb{d}t}}} \right\rbrack_{EXAMPLE}}$

-   -   The product of the required thrust force and its total duration;        i.e., t_(e)−t₀, is the required impulse.

Table 9 shows the calculated SSF, CSV, and CRR values for a targetvehicle and four different example vehicles. Table 10 shows the kineticenergy of each vehicle with the target critical roll rate value (i.e.,CRR_(TARGET)=2.48 rad/s), the potential energy of each vehicle at itscritical roll position, and the required work done by the thrusters tomake up the difference of the CRR value between the garget vehicle andeach example vehicle. FIG. 8 is a plot of the target design space foranti-roll thruster performance with impulse plotted versus thrust. FIG.8 depicts the target design space of required thrust force and impulseto make each of the example vehicles depicted in Table 9 perform likethe target vehicle using the generalized ECRR design strategy. Exemplarycommercial rocket motors, such as those listed in Table 11, which areeach available from Tally Defense Systems, can be utilized as thethrusters 14L, 14R in accordance with the principles of the presentinvention. Alternatively, specially designed solid, gas, or liquidpropellant rocket motors could be used to provide the required thrustforces.

TABLE 9 T h_(CG) Mass I_(CG) I_(O) CSV CRR mm mm kg kg-m{circumflex over( )}2 kg-m{circumflex over ( )}2 SSF m/s rad/s Target 1467 535 1577 5681868 1.37 5.50 2.48 Example 1 1419 664 1729 580 2212 1.07 4.18 2.17Example 2 1543 654 2204 1101 3355 1.18 4.99 2.14 Example 3 1422 690 2302749 3008 1.03 4.02 2.12 Example 4 1689 768 2563 1244 4584 1.10 4.71 2.02

TABLE 10 PE_(C), Potential W_(T), Required Work KE_(C), Kinetic EnergyGain at Done by Energy with Critical Critical Position the ThrustersVehicle Roll Rate (kJ) (kJ) (kJ) Target 5.76 5.76 0 Example 1 6.82 5.211.61 Example 2 9.28 6.78 2.50 Example 3 10.35 7.72 2.63 Example 4 14.149.38 4.76

TABLE 11 Talley Defense Systems ROCKET MOTORS Action Normal Motor Weight(lb) Time Impulse Thrust DIA. Length Propellant Program Loaded Burned(sec) (kN-sec) (kN) (mm) (mm) Type Mark 1 15.9 11.1 0.190 4.63 29 104356 HTPB M913 Rocket Propellant 1.7 1.87 1.09 91 109 HTPB Motor Weight2.2 IDS Rocket Propellant 0.375 1.72 5.12 101 178 HTPB Motor Weight 1.75SuperBarricade Propellant Weight 0.62 0.76 2.29 94 53 HTPB SuperPalisade.86 Short Range SuperBarricade Propellant Weight 0.62 1.67 3.90 94 104HTPB SuperStockade 1.77 Long Range

The role of the thruster system is in rollover avoidance. The thrustersare preferably used in combination with other stabilization systems aswell as airbag protection systems which are currently used in theautomotive industry. In particular, the thrusters can be utilized inorder to supplement these other vehicle stabilization systems during adetected potential rollover condition. In particular, currently utilizedvariable ride height suspension systems and electronic stability controland braking control systems are utilized as a first line of defenseagainst vehicle rollover, while the thrusters can be viewed as a lastcounter-measure that a vehicle can undertake to avoid an imminentrollover accident. The variable ride height suspension system can beutilized, for example, prior to a detected potential roll condition withelectronic stability control also being utilized in the time frame ofseveral thousand milliseconds to several hundred milliseconds prior tothe projected roll conditions. Furthermore, the thrusters can beemployed within the last few hundred milliseconds as a finalcounter-measure for counteracting vehicle roll forces. Furthermore,airbags can be utilized in order to protect passengers after thethrusters are employed. It should be appreciated that the system of thepresent invention would not be effective to prevent all severe rollevents, but could be potentially useful for some less severe rollevents. It will be appreciated that the thruster system could also beused for anti pitch. Furthermore, any safety for the occupant,surrounding vehicles and pedestrians would need to be considered forcarrying the thrusters on the vehicles.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A roll stabilization system for a motor vehicle, comprising: a firstthruster mounted on a first side of said motor vehicle; a secondthruster mounted on a second side of said motor vehicle; a controllersystem for detecting a potential roll condition of said motor vehicleand activating at least one of said first and second thrusters forgenerating a counteracting force for resisting the detected potentialrollover condition, wherein said first and second thrusters are eachmounted in side pillars of said motor vehicle.
 2. The roll stabilizationsystem according to claim 1, wherein said first and second thrusters arerocket motors.